The thing that I somewhat appreciated about iOS that it was an OS catered towards people, in the sense that it had splashes of color, elegance and so on...
Windows Phone and Android always felt more "industrial". More functional than iOS but less aesthetically pleasing. However with the arrival of more recent versions of Windows Phone the situation improved, while Android did have changes but remained more of the same.
Lollipop brings this whole new level of an amazing and cohesive design language, stunning animations and there is just this new level of " finesse" to it, there are things you can't really describe you have to use it to realise the potential.
I'm sure that there will be people that liked the old Android, or those that prefer iOS or Windows Phone but finally Android is on the same level of visual appeal(or better) as the competing operating systems.
For me, Material goes a much longer way than Metro UI ever did.